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kentronix

C11 XLT or 925XLT for a semi fixed garden scope

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Morning folks,

The short question, for a garden setup, not likely to be taken out of teh garden at all but quite probably moved between a few set locations (in the garden) every few weeks, is the C11 XLT on CGEM going to be annoying or should I stick with a C9.25 ?

The waffle,

Long time no post, unfortunately real life got in the way and I haven't done anywhere near as much observing or imaging as I would like. The main reason is my garden is very overlooked and I am uncomfortable staying out there with just the sound of goto motors for long periods. It also takes ages to get my scopes to the garden (through my house and small door) and then set up to point at the small area of sky I can see and then put away again. I should mention I live in london.

I have addressed the privacy issue and would now like to try to get something that makes it easy to go out there and gives me more time observing and imaging.

I currently mainly use my skywatcher 150p on an undersized alt/az goto mount, considering the sub £100 cost of the setup I am amazed at the results. My aims are split between imaging and observing, so far planets, the moon, and M42. I like as many object options and flexibility is important for me and I like trying different things and eeking out what I can from stuff. I have a canon 550d and spc webcam, both currently un-modded.

The new setup that I have decided on so far is the CGEM mount, and a Startravel 80 (to be used as a guide scope and possibly imaging later). These are hopefully quite uncontroversial. Any  cheaper alternatives to the st80 would be considered, I am somewhat over budget  :) As would second hand.

I have read up all I can about the two main scope options and despite my imaging aspirations think I can work with an Celestron XLT. With a little effort and a reducer I think it should be fine for me. I now the 925 is considered by many a bit of a "sweet spot" but aperture matters and the ignoring everything else I would get the C11.

I was all set on the C11, it is intended to be set up all the time, initially with a homemade foam cover covered in a thin groundsheet and one of those stacked chair waterproof covers tied down over the top. I will be asking questions about moisture later. I do intend to build a pvc pipe based semi solid cover later but it wont be for a while.

After inspecting the garden last night and working out exactly what portion of the sky I can see between the ever growing trees, the flats, my house, and the fences it became clear that there is no fixed spot that will regularly give me good targets.

My new plan is to have the tripod sat in fixed location markers for the different views and move it from one to another every now and then. They are about 20 ft apart maximum, on uneven ground (wheels wont work). Will both setups require the OTA to be removed from the tripod to safely move them ? And assuming so, will the C11 be awkward even when removed ?

I dont have any physical ailments apart from lack of elbow grease production, I am passionate about the hobby but with little time and lots of other things I am passionate about I want to design something that I will actually be bothered to use as intended, I am not sure if the C11 is just a bit too bulky.

Ideally removing the weights, and moving it in 1 unit would be by far the easiest.

Told you it was waffle but I figured you may be interested in my plans and have advice for me. In terms of hours looking upwards I am still a newbie.

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The 9.25 is more than manageable, I'm quite a skinny lad and I can move it about with no problem at all, I think the C11 would be *just* within my capabilities also so if you're built better than me you should have no problem at all! Might be a bit awkward the first few times as you get use to re-attaching the OTA. 

If I were to get another SCT I'd get a C11 for sure. Don't get me wrong, the C9.25 is more than sufficient, it's a mighty scope! The C11 is a little bulkier like you say so if that would affect how much you're going to use it then stick with the C9.25!

Either way enjoy your new purchase! 

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I have the 9.25 SCT on the AVX mount so no vastly different from your intended set up.

The mount can be moved with the weights on, but it is very heavy, so I move it in an out without weights.

No way could you move either with the OTA attached...unless you were built like a certain Terminator actor and young to boot!

The 9.25SCT OTA can be placed onto the mount by one person. It was a rather neat carry handle at the back end which helps you get a grip, but the heart still does a quick pitter patter as I mount it. I can only think the C11 would be a wee bit more massive. No doubt others will comment.

Even if you mark up points for the tripod legs you will still have to do a polar align.

If you think that 0.5 Deg = 1 Moon diameter then you can appreciate even small differences have a big effect when the intentions is long exposure astro photography. For visual it is OK.

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I'd say the bigger the better, so go for the C11. But I think you should take the OTA off the CGEM to move it.... Especially when the weights are off, you should have the RA/DEC gears unmatched when moving the CGEM to avoid damage... If your C11 Or C9.25 was on it with no weights, you're asking for damage.

I put a ADM vixen type dovetail on my OTA for my guide scope and using both dovetail as grip moving it is comfortable and secure... So if you're strong enough to do that with your C11 go for the biggest aperture.

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Hi Kentronix,

Both scopes you are considering are excellent. However if I had a choice it would be the C11, as an ota it is easily movable. If you did not like it you could easily sell and get the smaller scope with some cash left over. If you buy the 9.25 and wanted bigger it is scope + cash!!. I had a 10" LX200, always lusted after the 12". As for mounting have you considered a portable pillar?

Good luck with your choice, in reality you would not be disappointed with either scope.

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Thanks so much, really good advice, I am chuffed to see you actually read the waffle to see my circumstances. I am actually a little surprised, many people seem to push the 925 as almost as good in most situations but ignoring portability it just cannot be that simple.

I am no arnie but quite strong. If they need to be split anyway (which I now know they do) then the 925 has no advantage, I am sure I can handle a 11 on its own. I still  have my trusty 150p if I ever venture out with it and the startravel for holidays. My existing 150p is dovetailed to my modded mount so I should get the hang of it ok.

Point noted about the alignment, I will bare it in mind.

Dont worry, the second I get any images I will be back to ask what went wrong....  I mean to show them off   :grin:

Now, does anybody want to buy a kidney ?

:laugh:

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The C11, is great under dark skies, but in

a town, your better off with the C9.25.

I sold my C11, & bought a CPC 800 Edge.

Best thing I have ever done. Did wonder at

the time. Bigger is not always better,

sometimes. Got more use out of this, than

I ever did, with the other set up. This is

so easy, to set up & use.

Steve.

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Thanks and  Grotemobile and m.tweedy, I have just bought the C11, hopefully I can work around the light pollution.

I have some filters, quite high fences(now), and apart from 1 single security light (he will be getting a phone call) the immediate pollution isn't too bad, just general city light pollution, much of which the filter helps with.

The ST80 is my first refractor too so although it is primarily for guiding I am looking forward to getting out and about with it too. Find some dark skies and gawp upwards. I suspect it will be a while before that happens, plenty to learn about the C11. Now I am off to find the pdf manual so I can spend my weekend like a schoolboy on christmas eve  :)

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if you piggyback the ST80 onto the C11 you can use it for widefield views.

i ofen did/do that with my Megrez90 and love the contrast of the widefield then the zoomed in view

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I think I will have lots of options with this, although it seems there are lots of clouds that want to spoil it for me for the next few days.

I am watching the DHL van carry it across the country now, just got to get from exeter to london :)

So far I have to echo what everybody else has said about FLO, great knowledge, friendly and of course very keen prices.

Luckily my waterproof cover (quality stacked chair cover) arrived before it has.

I plan to have a thin blanket on top of the scope with a thin tarp over that. Then the chair cover. Depending on how it fits together I aim to put a pvc frame together for the chair cover and make a tiny roll off shelter. It all depends on sizes. I have chosen rather a big one  :shocked:

I hate waiting for stuff to arrive, we need DHL teleport delivery service.

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I have the 1100 CPC XLT and manage quite easily carrying the scope from my dining lounge down into the decking outside the conservatory. The knack is to place the scope onto the base without "dunking" which may lead to collimation issues. The scope is too heavy to carry legs and scope any distance, it can be moved  a couple of meters, no more. I have taken the scope into the garden to catch Jupiter which entails 6 steps down into the garden. The methodology is to make sure there are no trip hazards en route to your set area. I leave my scope out for 2-3 hours prior to observing. Collimation with bob knobs gives me perfect diffraction circles on a star after leaving my scope out for as long as reasonably possible, 6 hours the last time. Hope this helps.

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You briefly mention DS imaging with DSLR and these scopes would be about as bad as it gets for this purpose, especially from London. The precision needed to autoguide at a pixel scale like this is almost unreachable. Try this calculator http://www.12dstring.me.uk/fov.htmto find your arcsecs per pixel. Many people in the UK like 2"P/P because it approximates to what their seeing allows and it is guidable with normal budget mounts etc. More expert imagers might say 1"PP and it is possible to go below that with a lot of input. What does all this really mean? In DS imaging it really means that with a big slow SCT you will not get anywhere near the same standard of DS image as you'd get with a smaller, faster scope.

But a big SCT will out-image anything on the planets. Ask Mr Peach!

For visual they are portable but limiting in terms of field of view. From London the big faint stuff is out of reach anyway so I doubt that this matters. A big SCT has a lot going for it in view of what's possible from big LP.

One way to move them around (I did this myself in the UK) is to have the lot, tripod and all, mounted on a triangular wooden sled and to be moved as one using a proprietory sack truck. The idea came from Phil Harrington's excellent Star Ware book.

Olly

Edited by ollypenrice

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I use a second hand year 2000 StarBright (NON-XLT) C11 SCT (ex-CG-11 OTA) on CG-5 ASGT and have done for many months now ;-

https://picasaweb.google.com/101932667412801910198/CelestronC11OnCG5ASGTWithScopeStuff6InchCounterweightExtensionBar

(click on pix to see the text description and a bigger pic)

I use 3 permanent marker pen circles on the patio, tripod tips always go in the same 3 circles, Polar alignment was done by ASPA and is NOT done from night to night, only once in a while just for checking / kicks / practice. Same with the Alignment, done once, and NOT done each night. I use Hibernate at the end of each session. GOTO is adequate at 100x or so, and great with my Meade 7" Mak at 300x. Vibrations damp in 1 second at 250x or more with the 7", and 2 seconds for the C11 at 700x. Totally smooth tracking at 700x with C11, same tracking noise and volume as 8" LX90. Very good optics on my C11, sharp Airy disc at 700x, hard round balls of light at 350x on Epsilon Lyrae, rather low Spherical Aberration it seems.

I lift the mount onto the patio with the EQ head bolted to the tripod. I use a 6" ScopeStuff counterweight extension bar and 1.8, 3.4 and 5Kg counterweights. Colored tape marks the position for the counterweights on the bar so no balancing needed. I use Dew-Not dew heater strip and a controller and cardboard dew shield.

The C11 is pretty easily lifted, and as long as only a quick-release finder bracket is on the OTA then it's easy to manipilate. Mounting is slightly hair raising (however I am well used to it so no problems really) but solid with no wobbles (it has Losmandy style dovetail and radius blocks, previous owner Chris in Skelmersdale (I think) added a Vixen style short dovetail into the bottom of the Losmandy one with 2 tapped holes and 1/4 inch diameter bolts approx.

Setting the lot up takes me about 20 mins, take down approx. 15 mins. It's my daily excercise. An 8" LX90 my friend had was not all that more convenient to setup, not any lighter, nor easier to mount, and took just about as long to do, plus it needed alignment every night.

I am only 8 1/2 stone and can manage all this fairly easily. But there is a hassle factor, and the C11 has to be cooled for an hour with my homemade Lymax style cooler and also with a cheap Ebay medical gel "ice" pack, it's not grab and go. The 8" better would be a MUCH better choice for "imaging" (at F5 with Mallincam would be my choice), the 8" or 9.25" would be faster and easier to deal with for visual, when lifting and mounting. Indeed, I found the C11 very intimidating at first and didn't mount it for months when I first got the CG5, I used to use my 7" Mak instead. But my C11 outperforms my very nearly perfect Mak's optics on Jupiter, and of course on M13 where the latter is much brighter etc. C11 is very large and bulky and awkward to mount, the 7" Mak (has same dia. tube as 8" SCT) is much much easier to handle.

Nice choice on that C11. I am thinking about the M12 next (OTA only, not fork mounted);-

https://picasaweb.google.com/101932667412801910198/Meade12LX200ClassicAdvertAstronomyMagazineUSA1993#6028130721406921618

...on NEQ6 maybe (I can even add a C14 later to the NEQ6 since the latter has dual dovetails as standard).

Regards,

Alistair G.

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